Stanford / Engineering

Review: Definition Of The DFT

By Brad G. Osgood | The Fourier Transform and its Applications Lecture 20 of 30

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Lecture Description

Review: Definition Of The DFT, Sample Points, Relationship Between N And Spacing In Time/Frequency, Complex Exponentials In The Discrete DFT, DFT Written With Discrete Complex Exponential Vector, Periodicity Of Inputs And Outputs In The DFT (More On This In Next Lecture), Orthogonality Of The Vector Of Discrete Complex Exponentials, Note On Orthonormality Of Discrete Complex Exponential Vector (Or Lack Thereof), Consequence Of Orthogonality: Inverse DFT

Course Description

The goals for the course are to gain a facility with using the Fourier transform, both specific techniques and general principles, and learning to recognize when, why, and how it is used. Together with a great variety, the subject also has a great coherence, and the hope is students come to appreciate both.

Topics include: The Fourier transform as a tool for solving physical problems. Fourier series, the Fourier transform of continuous and discrete signals and its properties. The Dirac delta, distributions, and generalized transforms. Convolutions and correlations and applications; probability distributions, sampling theory, filters, and analysis of linear systems. The discrete Fourier transform and the FFT algorithm. Multidimensional Fourier transform and use in imaging. Further applications to optics, crystallography. Emphasis is on relating the theoretical principles to solving practical engineering and science problems.

Related Resources

Transcript   |  Problem Set 6   |  Problem set 6 Solutions

Course Index

  1. The Fourier Series
  2. Periodicity; How Sine And Cosine Can Be Used To Model More Complex Functions
  3. Analyzing General Periodic Phenomena As A Sum Of Simple Periodic Phenomena
  4. Wrapping Up Fourier Series; Making Sense Of Infinite Sums And Convergence
  5. Continued Discussion Of Fourier Series And The Heat Equation
  6. Correction To Heat Equation Discussion
  7. Review Of Fourier Transform (And Inverse) Definitions
  8. Effect On Fourier Transform Of Shifting A Signal
  9. Continuing Convolution: Review Of The Formula
  10. Central Limit Theorem And Convolution; Main Idea
  11. Correction To The End Of The CLT Proof
  12. Cop Story
  13. Setting Up The Fourier Transform Of A Distribution
  14. Derivative Of A Distribution
  15. Application Of The Fourier Transform: Diffraction: Setup
  16. More On Results From Last Lecture (Diffraction Patterns And The Fourier Transforms)
  17. Review Of Main Properties Of The Shah Function
  18. Review Of Sampling And Interpolation Results
  19. Aliasing Demonstration With Music
  20. Review: Definition Of The DFT
  21. Review Of Basic DFT Definitions
  22. FFT Algorithm: Setup: DFT Matrix Notation
  23. Linear Systems: Basic Definitions
  24. Review Of Last Lecture: Discrete V. Continuous Linear Systems
  25. Review Of Last Lecture: LTI Systems And Convolution
  26. Approaching The Higher Dimensional Fourier Transform
  27. Higher Dimensional Fourier Transforms- Review
  28. Shift Theorem In Higher Dimensions
  29. Shahs
  30. Tomography And Inverting The Radon Transform
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